Memory Cell Low Voltage Read Current Segmentation

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Solution Overview

Problem

Existing memory cell technologies face challenges in reading data efficiently under low voltage conditions due to significant decay of read current along long charging paths, leading to increased time for data retrieval.

Innovation Solution

The memory cell design incorporates a programming selection transistor, a following gate transistor, an antifuse varactor, and a reading circuit with specific voltage control signals and transistor configurations to form a stable read current, including a reading transistor and a reading selection transistor to manage parasitic capacitance and reduce unintentional triggering.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If the memory cell operates with low voltage, then power consumption is reduced, but the read current becomes too small and decays significantly along the column, increasing reading time

Engineering Contradiction:
Improvepower consumptionVSAvoidreading time
Core Design Contradiction:
Loss of energyVSLoss of time

Solution Approach 1:

The memory cell is segmented into multiple transistors (first transistor, second transistor, third transistor, fourth transistor) with specific coupling relationships. The second transistor is coupled to the third transistor, and the fourth transistor is coupled to both the first and third transistors, creating a segmented current path that reduces the impact of parasitic capacitance and enables low-voltage operation with sufficient read current.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The third transistor acts as an intermediary element between the antifuse transistor and the bit line. This intermediate transistor amplifies and transfers the read current more effectively, compensating for the decay caused by parasitic capacitance in the column, thereby enabling reliable low-voltage operation.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Reliability

If the read current charges parasitic capacitors along the column, then data can be read, but the long charging path causes significant decay and increases reading time

Engineering Contradiction:
Improvedata reading capabilityVSAvoidreading time
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The read current path is segmented through multiple transistors, with the second transistor coupled to the third transistor and the fourth transistor coupled to both the first and third transistors. This segmentation creates multiple current paths that can charge parasitic capacitors more efficiently, reducing the overall charging time and decay effects.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The memory cell uses a composite transistor configuration combining NMOS and PMOS transistors in specific arrangements. The fourth transistor is coupled to both the first and third transistors, creating a composite structure that provides both high current drive capability and low voltage operation, effectively charging parasitic capacitors faster.

Inventive Principle:
Principle #40Composite materials

Data Source

PatentEP3018657B1Memory cell capable of operating under low voltage conditions
Publication Date: 2020.11.25 EMEMORY TECH INC
  • EP3018657B1 patent drawingFigure 1
  • EP3018657B1 patent drawingFigure 2
  • EP3018657B1 patent drawingFigure 3

AI summary

A memory cell includes a programming selection transistor, a following gate transistor, an antifuse element, and a reading circuit. A charging current formed by the antifuse element may trigger the reading circuit to form a stable read current during a reading operation of the memory cell so that the time for reading data from the memory cell is shortened. A discharging process may be operated in the beginning of the reading operation of the memory cell so that the window of time for reading data from the memory cell can be widened.